Metal or metal-plated reinforcement with sulfur polybenzoxazine-coated surface

ABSTRACT

in which the two oxazine rings are connected together via a central aromatic group, the benzene ring of which bears one, two, three or four groups of formula —Sx—R in which “x” is an integer from 1 to 8 and R represents hydrogen or a hydrocarbon-based group including 1 to 10 carbon atoms and optionally a heteroatom chosen from O, S, N and P. Such a reinforcement can be used for the reinforcement of a rubber article, in particular a motor vehicle tire.

1. FIELD OF THE INVENTION

The present invention relates to thermosetting resins, which may be usednotably in adhesive systems intended in particular for the adhesivebonding of metal to rubber.

The invention relates more particularly to polymer-coated metallic ormetallized reinforcers that may be used as adhesive layers inmetal/rubber composites intended for the manufacture of rubber articlessuch as pneumatic or non-pneumatic tyres, for motor vehicles.

2. PRIOR ART

Metal/rubber composites, in particular for motor vehicle tyres, are wellknown. They are usually composed of a matrix made of unsaturated rubber,generally diene rubber, which can be crosslinked with sulfur, includingmetal reinforcing elements (or “reinforcers”) such as yarns, films,tapes or cords made of carbon steel.

As they are subjected to very high stresses during the rolling of thetyres, notably to repeated actions of compression, bending or variationsin curvature, these composites must, in a known manner, satisfy a largenumber of sometimes contradictory technical criteria, such asuniformity, flexibility, flexural strength and compressive strength,tensile strength, wear resistance and corrosion resistance, and mustmaintain these performance qualities at a very high level for as long aspossible.

It is easily understood that the adhesive interphase between rubber andreinforcers plays a predominant role in the endurance of theseperformance qualities. The conventional process for connecting rubbercompositions to carbon steel consists in coating the surface of thesteel with brass (copper/zinc alloy), the bonding between the steel andthe rubber matrix being provided by sulfurization of the brass duringthe vulcanization or curing of the rubber. In order to improve theadhesion, use is generally made, in addition, in these rubbercompositions, of organic salts or metal complexes, such as cobalt salts,as adhesion-promoting additives.

However, it is known that the adhesion between the carbon steel and therubber matrix is liable to weaken over time as a result of the gradualdevelopment of the sulfides formed, under the effect of the variousstresses encountered, notably mechanical and/or thermal stresses, itbeing possible for the above degradation process to be accelerated inthe presence of moisture.

Moreover, the use of cobalt salts renders the rubber compositions moresensitive to oxidation and to ageing, and significantly increases thecost thereof, not to mention that it is desirable to eliminate, in thelong run, the use of such cobalt salts in rubber compositions due to therecent change in European regulations relating to metal salts of thistype.

For all the reasons set out above, manufacturers of metal/rubbercomposites, in particular motor vehicle tyre manufacturers, are seekingnovel adhesive solutions in order to adhesively bond metal reinforcersto rubber compositions, while overcoming, at least in part, theabovementioned drawbacks.

Thus, the recently published patent applications WO 2014/063963, WO2014/063968, WO 2014/173838 and WO 2014/173839, filed by the ApplicantCompanies, have described novel polymers bearing urea, urethane orthiourea units, and also their starting monomers, which meet the aboveobjectives. Used notably as adhesion primer on metal in metal/rubbercomposites, these polymers make it possible very advantageously toadhesively bond the metal to the rubber matrices by subsequently usingsimple textile adhesives, such as “RFL” (resorcinol/formaldehyde latex)adhesives or other equivalent adhesive compositions, or else directly(that is to say, without employing such adhesives) to these rubbermatrices when the latter contain, for example, appropriatefunctionalized unsaturated elastomers, such as epoxidized elastomers.Thus, the cobalt salts (or other metal salts) can notably be left out ofthe rubber compositions intended to be connected to brass-coated metalreinforcers.

In continuing their research, the Applicant Companies have found a novelpolymer, of thermosetting type, which at room temperature has the sameadhesive performance, with respect to metal and rubber, as theabovementioned polymers, but which has, once thermoset (crosslinked),further improved thermal and chemical stability. Moreover, its specificmicrostructure makes it possible very advantageously to adjust theflexibility of the molecule depending on the particular applicationstargeted.

3. BRIEF DESCRIPTION OF THE INVENTION

Thus, the present invention relates to a metallic or metallizedreinforcer, at least the surface of which is at least partiallymetallic, at least said metallic part being coated with apolybenzoxazine including at least repeating units including at leastone unit corresponding to formula (I) or (II):

in which the two oxazine rings are connected together via a centralaromatic group, the benzene ring of which bears one, two, three or fourgroups of formula —S_(x)—R in which “x” is an integer from 1 to 8 and Rrepresents hydrogen or a hydrocarbon-based group including 1 to 10carbon atoms and optionally a heteroatom chosen from O, S, N and P.

The invention relates in particular to such a reinforcer in the form ofa yarn, film, tape or cord, at least a part of the surface of which ismade of steel, in particular of carbon steel, it being possible for saidsteel to be a bright steel, i.e. uncoated steel, or else to be coatedwith at least one second metal, referred to as surface metal, the latterbeing preferentially selected from the group consisting of aluminium,copper, zinc and alloys of at least one of these metals with at leastone other metal.

By virtue of the above polybenzoxazine, the reinforcer of the inventionis capable of adhesively bonding matrices of ethylenically unsaturatedpolymers such as rubber, notably without the use of cobalt salts inthese polymer matrices being necessary.

The invention also relates to the use of such a reinforcer for thereinforcement of a rubber article, in particular a pneumatic ornon-pneumatic motor vehicle tyre.

The invention also relates to any rubber article, in the uncured(non-crosslinked) state or cured (crosslinked) state, in particular anypneumatic or non-pneumatic motor vehicle tyre, which is reinforced withat least one such reinforcer.

The invention and the advantages thereof will be easily understood inthe light of the detailed description and the implementation exampleswhich follow, and also of FIGS. 1 to 12, which represent or depict:

-   -   the general principle for the synthesis of a benzoxazine        compound starting from three compounds, phenol, formaldehyde and        amine (R=residue of the amine) (FIG. 1a );    -   the (ring-opening) mechanism for opening, by heat input, the        oxazine ring of such a benzoxazine compound (FIG. 1b );    -   a general scheme for the synthesis, starting from a specific        phenol (the symbol “G” will be described in detail later),        paraformaldehyde and a specific aromatic diamine sulfide, of a        benzoxazine of formula (A-0) (Monomer denoted by “M-0”) that can        be used for the synthesis of a polybenzoxazine sulfide that is        suitable for the reinforcer of the invention (FIG. 2);    -   a possible scheme for the synthesis, starting from a halogenated        phenol (the symbol “Hal” representing a halogen), p-formaldehyde        and the preceding specific aromatic diamine sulfide, of a        particular halogenated benzoxazine of formula (A-1) (Monomer        denoted by M-1) that can be used for the synthesis of another        polybenzoxazine that is suitable for the reinforcer of the        invention (FIG. 3);    -   another possible scheme for the synthesis, starting from another        specific phenol (the symbol “A” will be described in detail        later), p-formaldehyde and the preceding specific aromatic        diamine sulfide, of another benzoxazine of formula (A-2)        (Monomer denoted by M-2) that can be used for the synthesis of        another polybenzoxazine that is suitable for the reinforcer of        the invention (FIG. 4);    -   another possible scheme for the synthesis, starting from a        halogenated phenol, p-formaldehyde and a particular example of        an aromatic diamine sulfide, of another example of a particular        halogenated benzoxazine of formula (A-3) (Monomer denoted by        M-3) that can be used for the synthesis of a polybenzoxazine        that is suitable for the reinforcer of the invention (FIG. 5);    -   another possible scheme for the synthesis, starting from another        specific phenol, p-formaldehyde and the preceding specific        example of an aromatic diamine sulfide, of another example of a        benzoxazine of formula (A-4) (Monomer denoted by M-4) that can        be used for the synthesis of a polybenzoxazine that is suitable        for the reinforcer of the invention (FIG. 6);    -   another possible scheme for the synthesis, starting from a        particular example of a phenol (Compound 1: methoxyphenol        bearing ethylenic unsaturation), p-formaldehyde (Compound 2) and        the preceding particular example (Compound 3) of an aromatic        diamine disulfide, of another example of a benzoxazine of        formula (A-5) (Monomer denoted by M-5) that can be used for the        synthesis of a polybenzoxazine sulfide that is suitable for the        reinforcer of the invention (FIG. 7);    -   a scheme for the general synthesis of an example of a        polybenzoxazine sulfide (Polymer denoted by P-1) that is        suitable for the reinforcer of the invention, starting from the        preceding halogenated benzoxazine of formula (A-6) (Monomer M-6)        and from another monomer of general formula (B) (Monomer denoted        by N) of the aromatic diol or thiol type; and also this example        of a polybenzoxazine sulfide (Polymer denoted here by P-1′)        according to the invention once its oxazine rings have been        opened after heat treatment of the polymer P-1 (FIG. 8);    -   a scheme for the synthesis of another polybenzoxazine that is        suitable for the reinforcer of the invention (Polymer P-2′),        with its oxazine rings opened, obtained by homopolymerization of        the preceding particular halogenated benzoxazine of formula        (A-5) (Monomer M-5) (FIG. 9);    -   an example of synthesis, starting from brominated phenol        (compound 4), p-formaldehyde (compound 2) and a specific        aromatic diamine disulfide (compound 3), of a particular        brominated benzoxazine of formula (A-7) (Monomer denoted by M-7)        which may be used for the synthesis of polybenzoxazines (Polymer        P-3 and P-3′ of FIG. 11) that are suitable for the reinforcer of        the invention (FIG. 10);    -   finally, an example of synthesis of a polybenzoxazine sulfide        (Polymer by P-3) that is suitable for the reinforcer of the        invention, starting from the preceding particular halogenated        benzoxazine of formula (A-7) (Monomer M-7) and from another        particular monomer of formula (B-1) (Monomer N-1) of the        sulfur-based aromatic diol type (bearing a thioether function),        and also the structure of this polymer once its oxazine rings        have been opened (Polymer denoted by P-3′) (FIG. 11);    -   in radial section, an example of a tyre according to the        invention, incorporating a reinforcer in accordance with the        invention (FIG. 12).

4. DETAILED DESCRIPTION OF THE INVENTION

It will first of all be recalled that benzoxazines are compounds ofgeneral formula:

The appended FIG. 1a recalls the general principle of the synthesis of abenzoxazine, in this instance starting (condensation reaction) from onemolecule of phenol, from two molecules of formaldehyde and from an amine(R denoting the residue of the amine), with elimination of two moleculesof water.

FIG. 1b for its part recalls the mechanism for opening the oxazine ring(ring-opening) of such a compound during a heat input (represented bythe symbol Δ).

Numerous benzoxazine compounds or monomers can thus be synthesized usingvarious phenols and amines according to their types of substituents.These substituting groups may subsequently provide polymerizable sitesand make possible the synthesis of various benzoxazine polymers (orpolybenzoxazines).

Benzoxazines and polybenzoxazines which result therefrom are productswhich are today well known to a person skilled in the art; to cite but afew publication examples, mention may be made of the papers“Polybenzoxazines—New high performance thermosetting resins: synthesisand properties”; N. N. Ghosh et al., Prog. Polym. Sci., 32 (2007),1344-1391, or “Recent Advancement on Polybenzoxazine—A Newly DevelopedHigh Performance Thermoset”, Y. Yaggi et al., J. Polym. Sci. Part A:Polym. Chem.: Vol. 47 (2009), 5565-5576, and also, for example, of thepatents or patent applications U.S. Pat. No. 5,543,516 and WO2013/148408.

As explained in detail in the above documents, polybenzoxazines have theremarkable ability, at high temperature (for example, typically greaterthan 150° C., or even greater than 200° C., depending on theirparticular microstructure), to open their oxazine rings and to thusresult in thermosetting polyphenol resin structures.

The specific polybenzoxazine that is suitable for the reinforcer of theinvention is derived from a benzoxazine (referred to as Monomer M in thepresent application) of sulfide type which corresponds to the followinggeneric formula (A):

in which formula each benzene nucleus of the two oxazine rings bears atleast one (i.e. one or more) radical G; the benzoxazine itself thusbears at least two radicals G.

The (at least) two radicals G, which may be identical or different, arechosen from the group consisting of:

-   -   halogens;    -   groups —OR₁, —SR₁, —NR₂R₃; R₁, R₂ and R₃, which may be identical        or different, representing an alkyl containing 1 to 4 carbon        atoms; and    -   aliphatic hydrocarbon-based groups including 1 to 8 carbon        atoms, or cycloaliphatic hydrocarbon-based groups including 3 to        8 carbon atoms, or aromatic hydrocarbon-based groups including 6        to 12 carbon atoms; these saturated or ethylenically unsaturated        hydrocarbon-based groups also optionally including at least one        heteroatom chosen from O, S, N and P.

In this formula (A) as described previously for formulae (I) and (II) ofthe polymer that is suitable for the reinforcer of the invention, thetwo oxazine rings are connected together via a central aromatic group,the benzene ring or nucleus of which (also referred to as the centralbenzene ring or nucleus) bears one, two, three or four groups of formula—S_(x)—R in which “x” is an integer from 1 to 8 and R representshydrogen or a hydrocarbon-based group including 1 to 10 carbon atoms andoptionally a heteroatom chosen from O (oxygen), S (sulfur), N (nitrogen)and P (phosphorus).

Similarly, it may be noted in this formula (A) that the two nitrogenatoms of the oxazine rings are, relative to each other, in any position(i.e. ortho, meta or para) on the central benzene nucleus. However,preferably, these two nitrogen atoms are in the meta-position relativeto each other; in other words, the starting benzoxazine (Monomer in thiscase denoted by M-0) from which is derived the polybenzoxazine that issuitable for the reinforcer of the invention then preferentiallycorresponds to the generic formula (A-0) below:

The appended FIG. 2 gives the scheme for the general synthesis of thisbenzoxazine of formula (A-0), with heat input and with elimination ofwater, starting from a specific phenol bearing at least one (i.e. one ormore) radical G, paraformaldehyde and, finally, a specific aromaticdiamine sulfide of formula:

in which formula, needless to say, the benzene ring bears one, two,three or four groups of formula —S_(x)—R as defined previously, and maybear other optional substituents (by way of example a methyl or ethylgroup).

In this benzoxazine of formula (A) or (A-0), as for formulae (I) and(II) of the polymer that is suitable for the reinforcer of theinvention, the central benzene nucleus preferentially bears two groupsof formula —S_(x)—R, these two groups more preferentially being in themeta-position relative to each other on the benzene nucleus. Accordingto another preferential embodiment, “x” is within a range from 1 to 4,more preferentially equal to 1 or 2. R is preferentially an alkyl morepreferentially containing 1 to 5 carbon atoms, even more preferentiallya methyl or ethyl, in particular a methyl.

The polybenzoxazine (Polymer P) that is suitable for the reinforcer ofthe invention, derived from the benzoxazine of formula (A) describedpreviously, thus has the essential feature of including structuralrepeating units including at least one unit corresponding to formula (I)(before opening of the oxazine rings) or formula (II) (after ringopening) below:

The term “polymer” should be understood in the present patentapplication as meaning any homopolymer or copolymer, notably blockcopolymer, with repeating structural units including at least one unitof formula (I) or (II) above; needless to say, the polymer may includeboth units of formula (I) and units of formula (II).

In formula (II) above, a person skilled in the art will immediatelyunderstand that the two symbols “*” (which may be identical ordifferent) represent any attachment of the unit to a carbon atom or to aheteroatom (preferably chosen from O, S, N and P), this attachment orbond resulting from the opening of the oxazine rings during a sufficientinput of heat (A).

In addition, in the above formulae (I) and (II), as for the monomer offormula (A), one or more hydrogen atoms of at least one or of eachbenzene nucleus of the two oxazine rings, and also those of the centralbenzene ring, may optionally also be substituted with varioussubstituents (by way of example a methyl or ethyl group), notably withfunctional groups (by way of example a vinyl group) capable of promotingthe adhesion of the polymer to the metal and/or to the rubber.

Similarly, as for the preceding monomer of formula (A), it may be notedin these formulae (I) and (II) that the two nitrogen atoms of theoxazine rings are, relative to each other, in any position (i.e. ortho,meta or para) on the central benzene nucleus which separates them.

However, preferably, these two nitrogen atoms are in the meta-positionrelative to each other on the central benzene nucleus; in other words,the polybenzoxazine that is suitable for the reinforcer of the inventionthen includes at least repeating structural units including (at least)one unit corresponding to formula (I-bis) (before opening of the oxazinerings) or formula (II-bis) (after opening of the rings) below:

In the preceding formula (A) or (A-0), preferably, each benzene nucleusof the two oxazine rings bears only one radical G or at most two, morepreferentially only one radical G.

This radical (radical G) is even more preferentially located in the paraposition relative to the oxygen of the oxazine ring. In such a case, itwill be understood that the polybenzoxazine that is suitable for thereinforcer of the invention thus has the essential feature of includingat least repeating structural units including (at least) one unitcorresponding to formula (I-a) (before opening of the oxazine rings) orformula (II-a) (after ring opening) below:

Even more preferentially, “x” is equal to 1 and R represents a methyl.

Thus, as examples of aromatic diamine sulfides that are suitable for thesynthesis of a benzoxazine of formula (A) or (A-0) in which, accordingto a particularly preferential embodiment, “x” is equal to 1 and Rrepresents a methyl, mention will be made in particular of the compounds3,5-bis(methylthio)-2,4-toluenediamine,3,5-bis(methylthio)-2,6-toluenediamine and mixtures thereof,corresponding, respectively, to formulae (a) and (b) below:

In other words, according to a particularly preferential embodiment, ifthe benzoxazine of formula (A-0) is derived from at least one of theabove two isomers or from mixtures thereof, then the polybenzoxazinethat is suitable for the reinforcer of the invention includes repeatingunits including at least one unit corresponding to formula (I-a-1) or(I-b-1) (before opening of the oxazine rings), (II-a-1) or (II-b-1)(after ring opening) below:

According to a preferential embodiment, the (at least two) radicals G,which may be identical or different, represent a halogen such asbromine, chlorine, fluorine or iodine.

The appended FIG. 3 is a scheme of the general synthesis, with heatsupply and with elimination of water, starting from a halogenated phenolbearing at least one (i.e. one or more) halogen (represented by thesymbol “Hal”), p-formaldehyde and the specific aromatic diamine sulfideof the preceding FIG. 2, of a particular halogenated benzoxazine offormula (A-1) (Monomer denoted by M-1) which may be used for thesynthesis of a polybenzoxazine that is suitable for the reinforcer ofthe invention. This halogen (Hal) is more preferentially bromine orchlorine, even more preferentially bromine; the latter even morepreferentially being in the para position relative to the oxygen of eachoxazine ring.

According to another preferential embodiment, the (at least two)radicals G, which may be identical or different, represent a groupchosen from —OR₁, —SR₁, —NR₂R₃; R₁, R₂ and R₃, which may be identical ordifferent, representing an alkyl containing 1 to 4 carbon atoms.

According to another preferential embodiment, the (at least two)radicals G, which may be identical or different, represent an aliphatichydrocarbon-based group (represented by the symbol “A”) including 1 to 8carbon atoms, or a cycloaliphatic hydrocarbon-based group including 3 to8 carbon atoms, or an aromatic hydrocarbon-based group including 6 to 12carbon atoms, this saturated or ethylenically unsaturatedhydrocarbon-based group “A” being able optionally to include a (at leastone) heteroatom chosen from O, S, N and P.

The appended FIG. 4 is a scheme of the general synthesis, with heatsupply and with elimination of water, starting from a halogenated phenolbearing at least one (i.e. one or more) such group “A”, paraformaldehydeand the specific aromatic diamine sulfide of the preceding FIGS. 2 and3, of a particular benzoxazine of formula (A-2) (Monomer denoted by M-2)which may be used for the synthesis of a polybenzoxazine that issuitable for the reinforcer of the invention.

FIG. 5 is another possible scheme for the synthesis, starting from ahalogenated phenol, paraformaldehyde and a specific example of anaromatic diamine disulfide, namely3,5-bis(methylthio)-2,6-toluenediamine of the preceding formula (b), ofanother example of a particular halogenated benzoxazine of formula (A-3)(Monomer denoted by M-3) that can be used for the synthesis of apolybenzoxazine that is suitable for the reinforcer of the invention.

FIG. 6 is another possible scheme for the synthesis, starting fromanother phenol (the symbol “A” has been described previously),paraformaldehyde and 3,5-bis(methylthio)-2,6-toluenediamine of thepreceding formula (b), of another example of a benzoxazine of formula(A-4) (Monomer denoted by M-4) that can be used for the synthesis of apolybenzoxazine that is suitable for the reinforcer of the invention.

According to a preferential embodiment, the (at least two) groups “A”,which may be identical or different, represent an saturated orethylenically unsaturated aliphatic hydrocarbon-based group, including 1to 6 and in particular 1 to 4 carbon atoms, which may optionally includeat least one (i.e. one or more) heteroatom chosen from O, S, N and P.

Thus, according to another particular and preferential embodiment, thepolymer that is suitable for the reinforcer of the invention is derivedfrom a benzoxazine disulfide which corresponds at least partly to one ofthe two formulae (A-5) and (A-5bis) (Monomers denoted, respectively, byM-5 and M-5bis) below:

FIG. 7 is a particular case of FIG. 6 which describes another scheme forthe synthesis, starting this time from a particular example of a phenol(Compound 1) corresponding to such a preferential definition (in thiscase, phenol bearing an ethylenic unsaturation and a methoxyl group),paraformaldehyde (Compound 2) and the particular example of thepreceding aromatic diamine disulfide (Compound 3), of another example ofa benzoxazine of formula (A-5) (Monomer denoted by M-5) which may beused for the synthesis of a polybenzoxazine sulfide that is suitable forthe reinforcer of the invention.

A person skilled in the art is well aware of how to widely adaptspecific formula (A) or (A-0) of the benzoxazine serving as startingmonomer for the synthesis of the polybenzoxazine of the reinforcer ofthe invention, by notably varying the formulae of the phenol (bearingthe radical(s) G) and of the diamine sulfide (bearing the group(s) offormula —S_(x)—R).

As examples of preferential aromatic diamine sulfides, mention hasalready notably been made of the compounds3,5-bis(methylthio)-2,4-toluenediamine,3,5-bis(methylthio)-2,6-toluenediamine, and mixtures thereof.

As examples of phenol compounds (in this case, for example,methoxyphenols) bearing groups “A” of the saturated or ethylenicallyunsaturated aliphatic hydrocarbon-based type, including 1 to 6 and inparticular 1 to 4 carbon atoms, which may optionally include at leastone (i.e. one or more) heteroatom chosen from O, S, N and P, examplesthat may be mentioned include the following compounds:

According to a preferential embodiment, the polybenzoxazine polymer thatis suitable for the reinforcer of the invention may be obtained bypolycondensation of a benzoxazine of formula (A) or (A-0) as describedin detail previously, as first monomer, and, as second monomer, anaromatic diol or thiol compound.

This aromatic diol or thiol compound more preferentially corresponds toformula (B):

HX₁—Ar₁—Z—Ar₂—X₂H  (B)

in which:

-   -   X₁ and X₂, which may be identical or different, represent O or        S;    -   Ar₁ and Ar₂, which may be identical or different, represent an        aromatic group, preferably phenylene;    -   Z represents O or (S)_(n), the symbol “n” representing an        integer greater than or equal to 1.

Thus, according to one particularly preferred embodiment, thepolybenzoxazine that is suitable for the reinforcement of the inventionis characterized by repeat units including at least one unitcorresponding to the particular formulae (I-1) (before opening of theoxazine rings) or (II-1) (after ring opening):

In this case also, it is clearly noted that, in the above formulae, thetwo nitrogen atoms of the oxazine rings are, relative to each other, inany position (i.e. ortho, meta or para) on the central benzene nucleuswhich separates them.

However, even more preferentially, in the above formulae (I-1) and(II-1) above, these two nitrogen atoms are in the meta-position relativeto each other on the central benzene nucleus which separates them. Inother words, the polybenzoxazine that is suitable for the reinforcer ofthe invention then includes repeating structural units including (atleast) one unit corresponding to formula (I-1bis) (before opening of theoxazine rings) or formula (II-1bis) (after ring opening) below:

In the above formulae (I-1), (II-1), (I-1bis) and (II-1bis), one or morehydrogen atoms of at least one or of each aromatic nucleus Ar₁ and Ar₂could be substituted with various substituents, which may be identicalor different, for example functional groups capable of promoting theadhesion of the polymer to the metal and/or to the rubber.

FIG. 8 is a scheme for the general synthesis of a polybenzoxazinesulfide (Polymer denoted by P-1) that is suitable for the reinforcer ofthe invention, of formula (I-1bis) above, starting from the precedinghalogenated benzoxazine of formula (A-6) (Monomer M-6) and from anothermonomer of general formula (B) (Monomer denoted by “N”) of the aromaticdiol or thiol type; and also this example of a polybenzoxazine sulfide(Polymer denoted here by P-1′ of formula II-1bis) once its oxazine ringshave been opened after heat treatment of the polymer P-1.

In the general formulae (I-1), (II-1), (I-1bis) or (II-1bis) above,preferentially at least one of the following features is satisfied:

-   -   Ar₁ and Ar₂ each represent an unsubstituted phenylene group;    -   X₁ and X₂ each represent either a sulfur atom, or an oxygen        atom;    -   Z represents O or S (i.e. “n” equal to 1), more preferentially        S.

More preferentially, it is all of the preferential features above whichare simultaneously satisfied.

As preferential examples, the compound of the preceding formula (B)corresponds to at least one of the particular formulae (B-1), (B-2) or(B-3) below:

According to another particular and preferential embodiment, thepolybenzoxazine polymer that is suitable for the reinforcer of theinvention may be obtained by homopolymerization of a benzoxazine offormula (A) or (A-0) as described above.

Thus, FIG. 9 illustrates a scheme for the synthesis of anotherpolybenzoxazine (Polymer P-2′ of formula II-2) which is suitable for thereinforcer of the invention, with its oxazine rings opened, this timeobtained by simple homopolymerization of the particular halogenatedbenzoxazine of the preceding formula (A-5) (Monomer M-5).

According to another particular and preferential embodiment, the polymerthat is suitable for the reinforcer of the invention is derived from abrominated benzoxazine polysulfide which corresponds at least partly toone of the two formulae (A-7) and (A-7bis) (Monomers denoted,respectively, by M-7 and M-7bis) below:

FIG. 10 precisely gives an example of synthesis, starting from thebrominated phenol (compound 4), p-formaldehyde (compound 2) and3,5-bis(methylthio)-2,6-toluenediamine (compound 3), of this brominatedbenzoxazine polysulfide of formula (A-7) (Monomer denoted by M-7) whichmay be used for the synthesis of polybenzoxazines (Polymer P-3 and P-3′of FIG. 11) that are suitable for the reinforcer in accordance with theinvention.

In these examples of FIG. 10, as for the preceding FIGS. 7 to 9, it isnoted in particular, according to a particularly preferential embodimentalready indicated, that each benzene nucleus of the two oxazine rings ofthe benzoxazine of formula (A) bears only one halogen (Hal), morepreferentially bromine, located in the para position relative to theoxygen of the oxazine ring.

Finally, FIG. 11 describes the synthesis of a polybenzoxazine sulfide(Polymer P-3) that is suitable for the reinforcer of the invention,starting from the particular halogenated benzoxazine of formula (A-7)(Monomer M-7) above and from another particular monomer of formula (B-1)(Monomer N-1) of the sulfur-based aromatic diol type (bearing athioether function), and also the structure of this polymer once itsoxazine rings have been opened (Polymer denoted by P-3′).

The syntheses of FIGS. 10 and 11 will be described in greater detail inthe implementation examples that follow.

Typically, the polybenzoxazine of the reinforcer of the invention mayinclude from ten to several hundred, preferably from 50 to 300,structural units bearing units of formula (I) and/or (II), in particularstructural units as represented as examples in FIGS. 8, 9 and 11.

The polybenzoxazine described previously may advantageously be used, asadhesion primer or as sole adhesive layer, for coating the reinforcer ofthe invention and adhering the latter to rubber.

In order to adhere the rubber to the polybenzoxazine layer, use may bemade of any known adhesive system, for example a conventional textileadhesive of “RFL” type comprising at least one diene elastomer such asnatural rubber, or any equivalent adhesive known for impartingsatisfactory adhesion between rubber and conventional polymers such aspolyester or polyamide, for instance the adhesive compositions describedin patent applications WO 2013/017421, WO 2013/017422, WO 2013/017423,WO 2015/007641, and WO 2015/007642.

Before the above adhesive coating process, it may be advantageous toactivate the surface of the polybenzoxazine layer, for examplephysically and/or chemically, to improve the adhesive uptake thereofand/or the final adhesion thereof to the rubber. A physical treatmentmay consist, for example, of a treatment by radiation such as anelectron beam, or by plasma; a chemical treatment may consist, forexample, of prior passage through a bath of epoxy resin and/orisocyanate compound.

A person skilled in the art will readily understand that the connectionbetween the reinforcer of the invention provided with itspolybenzoxazine layer and the rubber layer with which it is in contactwill be definitively provided during the final curing (crosslinking) ofthe rubber article in question.

The polybenzoxazine described previously is intended for any type ofmetal reinforcer, typically of filiform type, for instance a wire, afilm (by convention, having a width of greater than 5 cm), a tape (byconvention a narrower film having a width at most equal to 5 cm) or acord made of steel, notably of carbon steel, intended in particular forreinforcing a matrix of unsaturated rubber such as natural rubber.

The steel, notably carbon steel, may be a bright steel, i.e. uncoatedsteel, or else may be coated at least partially with at least one layer(therefore intermediate layer, positioned between steel andpolybenzoxazine layer) of a second metal, referred to as the surfacemetal, this surface metal being preferentially chosen from the groupconsisting of aluminium, copper, zinc and alloys of at least one ofthese metals with at least one other metal (which may or may not belongto this group). As a more preferential example, the surface metal isbrass.

The carbon steel is preferentially such as normally used in cords of“steel cord” type for motor vehicle tyres; however, it is, of course,possible to use other steels, for example stainless steels. When acarbon steel is used, its carbon content is preferably between 0.4% and1.2%, in particular between 0.5% and 1.1%. The invention applies inparticular to any steel of the normal tensile (“NT”), high tensile(“HT”), super high tensile (“SHT”) or ultra high tensile (“UHT”) steelcord type.

The invention also relates to any rubber article, in the uncured (i.e.non-crosslinked) state or cured (crosslinked) state, in particular anypneumatic or non-pneumatic motor vehicle tyre, comprising a reinforceraccording to the invention. This tyre of the invention may be intendedfor all types of motor vehicles, in particular passenger vehicles orindustrial vehicles such as heavy duty vehicles, civil engineeringvehicles, and other transport or handling utility vehicles.

By way of example, FIG. 12 represents very schematically (without beingtrue to a specific scale) a radial section of a tyre in accordance withthe invention, for example for a motor vehicle of the passenger vehicletype or for a heavy duty vehicle.

This tyre 1 comprises a crown 2 reinforced with a crown reinforcement orbelt 6, two sidewalls 3 and two beads 4, each of these beads 4 beingreinforced with a bead wire 5. The crown 2 is surmounted by a tread, notshown in this schematic figure. A carcass reinforcement 7 is woundaround the two bead wires 5 in each bead 4, the turn-up 8 of thisreinforcement 7 being, for example, positioned towards the outside ofthe tyre 1, which is represented here mounted on its wheel rim 9.

The carcass reinforcement 7 is, in a manner known per se, formed, forexample, from at least one rubber ply reinforced with reinforcersreferred to as “radial” reinforcers, that is to say that thesereinforcers are positioned virtually parallel to each other and extendfrom one bead to the other so as to form an angle of between 80° and 90°with the median circumferential plane (plane perpendicular to the axisof rotation of the tyre which is located halfway between the two beads 4and passes through the middle of the crown reinforcement 6).

The belt 6 is, for example, composed, also in a manner known per se, ofat least two superimposed and crossed rubber plies, known as “workingplies” or “triangulation plies”, reinforced with metal reinforcerspositioned substantially parallel to each other and inclined relative tothe median circumferential plane, it being possible for these workingplies to optionally be combined with other rubber plies and/or fabrics.The primary role of these working plies is to give the pneumatic tyre ahigh cornering stiffness. The belt 6 may comprise, for example, a rubberply, referred to as a “hooping ply”, reinforced with reinforcing yarnsreferred to as “circumferential” reinforcing yarns, that is to say thatthese reinforcing yarns are positioned virtually parallel to each otherand extend substantially circumferentially around the pneumatic tyre soas to form an angle preferably within a range from 0° to 10° with themedian circumferential plane. The primary role of these circumferentialreinforcing yarns is, it should be remembered, to withstand thecentrifuging of the crown at high speed.

The tyre 1 of the invention has, for example, the essential feature thatat least its belt (6) and/or its carcass reinforcement (7) comprises areinforcer in accordance with the invention. According to anotherpossible implementation example of the invention, it is the bead zonethat can be reinforced with such a reinforcer; it is, for example, thebead wires (5) that could be formed, in whole or in part, of a such areinforcer according to the invention.

5. IMPLEMENTATION EXAMPLES OF THE INVENTION

In the present patent application, unless expressly indicated otherwise,all the percentages (%) shown are mass percentages.

The following tests firstly describe the synthesis of two examples ofbenzoxazine compounds (Monomers M-5 and M-7), then that of apreferential polybenzoxazine (Polymer P-3) that is suitable for thereinforcers according to the invention, starting from the Monomer M-7.Lastly, adhesion tests are performed to illustrate the excellentadhesive performance of the reinforcers in accordance with theinvention.

5.1. Synthesis of a Benzoxazine Sulfide (Monomer M-5)

For this synthesis, a 100-ml three-necked round-bottomed flask, equippedwith a thermometer, a nitrogen inlet, a magnetic stirrer and acondenser, is provided.

The synthesis is performed according to the procedure depicted in FIG.7, as explained in detail below, starting with three compounds: aspecific ethylenically unsaturated phenol bearing a methoxyl group(compound 1; eugenol; Aldrich product E51791), paraformaldehyde(compound 2; Aldrich product 158127) and an aromatic diamine disulfide(compound 3; 3,5-bis(methylthio)-2,6-toluenediamine), in the presence oftwo solvents (anhydrous toluene and anhydrous ethanol).

Compound 3 was isolated, by chromatography on silica gel, from theproduct Ethacure 300 (supplier: Albemarle, Belgium), available in theform of a relatively viscous liquid of brownish colour; it is composedto approximately 96% of a mixture of3,5-bis(methylthio)-2,4-toluenediamine and3,5-bis(methylthio)-2,6-toluenediamine isomers (weight ratio ofapproximately 4/1 according to chromatographic analysis).

Compound 1 (2 eq., 4.93 g, i.e. 30 mmol) and then ethanol (51 ml) arepoured into the round-bottomed flask. The presence of ethanol isimportant in this instance, preventing the formation of an unstabletriazine-type intermediate product. Compound 3 (1 eq., 3.215 g, i.e. 15mmol), compound 2 (4 eq., 1.80 g, i.e. 60 mmol) and finally the toluene(102 ml) are subsequently introduced with stirring. The reaction mediumis heated (approximately 75° C.) at reflux for 4 h and, after distillingoff the ethanol at about 100° C. over 16 hours, the solvents andvolatile residues are then finally distilled off at 40° C. (under avacuum of 20 mbar) for evaporation. The final product is then washed(100 ml of methanol) and dried.

This powder is placed in methanol (50 ml per 4 g of powder) and themixture is heated at reflux (65° C.) for 30 min. The solution is thenleft to cool to room temperature (approximately 20° C.) forcrystallization of the monomer. The solid product obtained is isolatedby filtration (Buchner filter). After drying in a vacuum oven at 50° C.overnight, a powder is thus obtained, the ¹H NMR spectrum (500 MHz)(solvent: d8-THF) of which confirmed the chemical structure of theMonomer M-5 thus synthesized, with the following results:

2.07 (s, 3H), 2.38 (s, 6H), 3.25 (t, 4H), 3.71 (s, 6H), 3.94-4.01 (t,2H), 4.58-4.64 (dd, 2H), 4.81-4.86 (dd, 2H), 4.96-5.05 (m, 6H),5.85-5.97 (m, 2H), 6.37-6.40 (d, 2H), 6.55 (s, 2H), 6.72 (s, 1H).

5.2. Synthesis of a Halogenated Benzoxazine Sulfide (Monomer M-7)

For this synthesis, a 100-ml three-necked round-bottomed flask, equippedwith a thermometer, a nitrogen inlet, a magnetic stirrer and acondenser, is provided.

The synthesis is performed according to the procedure depicted in FIG.10, as explained in detail below, starting with three compounds: ahalogenated phenol (compound 4; 4-bromophenol; Aldrich product B75808),p-formaldehyde (compound 2; Aldrich product 158127) and an aromaticdiamine disulfide (compound 3; 3,5-bis(methylthio)-2,6-toluenediamine),in the presence of two solvents (anhydrous toluene and anhydrousethanol).

Compound 3 was isolated, by chromatography on silica gel, from theproduct Ethacure 300 (supplier: Albemarle, Belgium), available in theform of a relatively viscous liquid of brownish colour; it is composedto approximately 96% of a mixture of3,5-bis(methylthio)-2,4-toluenediamine and3,5-bis(methylthio)-2,6-toluenediamine isomers (weight ratio ofapproximately 4/1 according to chromatographic analysis).

Compound 4 (2 eq., 2.6 g, i.e. 15 mmol) and then ethanol (23 ml) arepoured into the round-bottomed flask. The presence of ethanol isimportant in this instance, preventing the formation of an unstabletriazine-type intermediate product. Compound 3 (1 eq., 1.6 g, i.e. 7.5mmol), compound 2 (4 eq., 0.90 g, i.e. 30 mmol) and finally the toluene(46 ml) are subsequently introduced with stirring. The reaction mediumis heated (approximately 75° C.) at reflux for 16 h and then thesolvents and volatile residues are distilled off at 110° C. under vacuum(1 mbar) for evaporation.

The final product is then placed in methanol (50 ml per 4.5 g ofproduct) and the mixture is heated at reflux (65° C.) for 30 min. Thesolution is then left to cool to room temperature (approximately 20° C.)for crystallization of the monomer. The solid product obtained isisolated by filtration (Buchner filter). A yellow powder is thusobtained, after drying in a vacuum oven at 50° C. overnight (reactionyield equal to approximately 82%).

The ¹H NMR spectra (500 MHz) of the Monomer M-7 thus synthesized,dissolved in a deuterated solvent, confirmed its chemical structure,with the following results:

in d8-THF:

2.06 (s, 3H), 2.39 (s, 6H), 4.03-4.14 (t, 2H), 4.59-4.63 (d, 2H),4.87-4.91 (dd, 2H), 5.01-5.05 (dd, 2H), 6.71-6.74 (d, 2H), 6.81 (s, 1H),7.15-7.21 (m, 4H);

in CD₂Cl₂:

2.06 (s, 3H), 2.39 (s, 6H), 4.03-4.14 (t, 2H), 4.53-4.58 (dd, 2H),4.92-4.95 (dd, 2H), 5.00-5.04 (dd, 2H), 6.68 (s, 1H), 6.74-6.77 (d, 2H),7.14-7.15 (d, 2H), 7.21-7.24 (dd, 2H).

5.3. Synthesis of a Polybenzoxazine Polysulfide (Polymer P-3)

This synthesis is performed according to the procedure depicted in theFIG. 11, as described in detail below, starting with two monomers: thebenzoxazine obtained in the preceding step (Monomer M-7) and thesulfur-bearing aromatic diol of formula (B-1) (4,4′-thiodiphenol;Monomer N-1); this being in the presence of sodium carbonate (Na₂CO₃;Sigma Aldrich product 13418), and the (anhydrous) solvents DMA(N,N-dimethylacetamide; Sigma Aldrich product 38839) and toluene (AcrosOrganics product No. 364411000). The two monomers (M-7 and N-1) aredried beforehand under vacuum (10 mbar) at 60° C. overnight, andlikewise for the sodium carbonate but at a temperature of 150° C.

The synthesis is performed in a 100-ml four-necked round-bottomed flask,equipped with a nitrogen inlet, a thermometer, a magnetic stirrer and aDean-Stark separator surmounted by a condenser and by a distillationbridge (provided with a heating mantle). The apparatus is dried undervacuum using a hot air gun until the thermometer reaches a temperatureof at least 100° C. in the reaction flask. The system is left to cool toroom temperature (20° C.) and the apparatus is then placed under astream of nitrogen throughout the synthesis.

First of all, the Monomer M-7 (1 eq., 1.5 g, i.e. 2.79 mmol) of formula(A-7) and then the Monomer N-1 of formula (B-1) (1 eq., 0.61 g, i.e.2.79 mmol) are then introduced into the round-bottomed flask. This isfollowed by addition of 20 ml of DMA (solvent of both monomers) andthen, as base, of Na₂CO₃ (3 eq., 0.89 g, i.e. 8.36 mol) suspended in 4ml of toluene. The system is purged under N2 for 5 min and the reactionmedium is then heated to 105° C. Once this temperature is reached(heating mantle temperature of approximately 115° C.), the distillationbridge of the Dean-Stark apparatus is heated to 110° C. (with theheating mantle) in order to facilitate the azeotropic distillation(water/toluene distillation) performed for approximately 90 min. Thetemperature of the reaction medium is then gradually increased, instages of 10° C. every 30 min, until 130° C. is reached. The reactionmedium is left at this temperature for 17 h and is then left to cool toroom temperature (20° C.). The reaction mixture is subsequentlydistilled at 90° C. (vacuum 3 mbar) to remove the solvents and volatileresidues, and the solid precipitate thus obtained is then washed with250 ml of distilled water; during this washing, to extract thecarbonate, acid (1% aqueous HCl) is added dropwise until neutral pH isreached. The precipitate is once again washed with 100 ml of distilledwater and dried under vacuum at 80° C. overnight (approximately 12 h).

The Polymer P-3 of FIG. 11 was thus obtained, as attested to by the ¹HNMR analysis (500 MHz) in the solvent d8-THF, which gave the followingresults:

1.92 (s, 3H), 2.26 (s, 6H), 3.74-3.81 (m, 4H), 4.01-4.03 (t, 2H),4.75-5.01 (m, 2H), 6-15-6.75 (m, 4H), 6.90-7.45 (br, 11H).

This Polymer P-3, in the form of a pale yellow powder, was also analysedby DSC (Differential Scanning calorimetry) between −80° C. and +350° C.with a ramp of 10° C./min (Mettler Toledo DSC “822-2” machine; nitrogenatmosphere). The analysis showed, in the first pass (between −80° C. and+350° C.), an apparent glass transition (Tg) at 163° C. followed byexothermicity (corresponding to the opening of the oxazine rings and tothe crosslinking of the polymer) above 200° C., with two maxima atapproximately 270° C. and 299° C. During the second and third DSCpasses, performed between −80° C. and +350° C., no apparent glasstransition was visible.

5.4. Test of Adhesion in a Metal/Rubber Composite

A portion (325 mg) of the Polymer P-3 prepared above was dissolved in 8ml of DMPU (1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone; SigmaAldrich product 41661) with 10% by weight of “DY 9577 ES” accelerator(Huntsman product), this being in order to form a solution, a fraction(0.6 ml) of which was subsequently deposited uniformly on a brass tape(film) having dimensions of 10 cm×2.5 cm and a thickness of 0.5 mm; theassembly was placed in an oven at 175° C. (air ventilation) for 5 minand then for an additional 5 min at 230° C. under vacuum in order,firstly, to remove any trace of solvent and, secondly, to at leastpartially (that is to say, completely or partially) open the oxazinerings of the polymer, this last step being accompanied by a pronouncedchange in colour of the polymer, which changes to dark orange.

After cooling to room temperature, the tape provided at the surface withits thin (thickness 5 to 10 μm) layer of polybenzoxazine thus formed wassubsequently subjected to a conventional two-stage adhesive coatingoperation (two baths adhesive coating), first of all by immersion in afirst aqueous bath (approximately 94% water) based on epoxy resin(polyglycerol polyglycidyl ether, approximately 1%) and on isocyanatecompound (caprolactam-blocked isocyanate compound, approximately 5%),this first adhesive coating step being followed by drying (2 min at 100°C.) and then a heat treatment (5 min at 200° C.). The tape thus treatedwas then immersed in a second aqueous bath of RFL adhesive(approximately 81% by weight of water) based on resorcinol(approximately 2%), on formaldehyde (approximately 1%) and on a rubberlatex (approximately 16% of NR, SBR and VP/SBR rubbers); finally, it wasdried in an oven at 130° C. for 2 min and then heat treated at 200° C.for 5 min.

The brass tape thus coated with the polybenzoxazine film and then coatedwith adhesive was subsequently placed between two layers of conventionalrubber composition for a belt reinforcement of a passenger vehicle tyre,this composition being based on natural rubber, on carbon black andsilica as filler and on a vulcanization system (sulfur and sulfenamideaccelerator); this composition was free of cobalt salt. The metal/rubbercomposite test specimen thus prepared was then placed under a press andthe whole was cured (vulcanized) at 150° C. for 30 min under a pressureof 20 bar.

After vulcanization of the rubber, excellent adhesive bonding betweenthe rubber matrix and the metal tape of the invention was obtained,despite the absence of cobalt salt in the rubber matrix; this isbecause, during peel tests (at 20° C.), it was found that the failureoccurred systematically in the rubber matrix itself and not at theinterphase between metal and rubber. Other adhesive bonding tests wereperformed on a bright (uncoated) steel tape; they also revealedexcellent adhesion to the rubber (systematic failure in the rubbermatrix).

In conclusion, the specific polybenzoxazine described in detail in thepresent patent application offers the metal reinforcers of the inventionthe major advantage of being able subsequently to be adhesively bondedto rubber matrices using simple textile adhesives, such as RFLadhesives, or else directly (that is to say, without employing suchadhesives) to these rubber matrices, for example when the latter containappropriate functionalized unsaturated elastomers, such as epoxidizedelastomers. Thus, use may be made of metal substrates optionally coatedwith adhesive metal layers such as brass, and also surrounding rubbermatrices free of metal salts, in particular of cobalt salts.

Moreover, this constituting a significant advantage compared to theother known polymers described in the introduction to the presentdocument, the polybenzoxazines according to the invention have thenoteworthy ability, at high temperature, to open their oxazine rings andto thus give a thermosetting polyphenolic resin structure. This givesthem better heat stability. Finally, their specific microstructure makesit possible, very advantageously, to adjust the flexibility of themolecule according to the particular applications targeted.

1.-20. (canceled)
 21. A metallic or metallized reinforcer, at least asurface of which is at least partially metallic, the at least partiallymetallic surface being coated with a polybenzoxazine sulfide, repeatingunits of which include at least one unit corresponding to formula (I) or(II):

in which the two oxazine rings are connected together via a centralaromatic group, the benzene ring of which bears one, two, three or fourgroups of formula —S_(x)—R in which x is an integer from 1 to 8 and Rrepresents hydrogen or a hydrocarbon-based group including 1 to 10carbon atoms and optionally a heteroatom chosen from O, S, N and P. 22.The reinforcer according to claim 21, wherein the central benzene ringbears two groups of formula —S_(x)—R.
 23. The reinforcer according toclaim 22, wherein the two groups of formula —S_(x)—R are in themeta-position relative to each other on the central benzene ring. 24.The reinforcer according to claim 21, wherein x is in a range from 1 to4.
 25. The reinforcer according to claim 21, wherein R is an alkylcontaining from 1 to 5 carbon atoms.
 26. The reinforcer according toclaim 25, wherein R represents a methyl or an ethyl.
 27. The reinforceraccording to claim 21, wherein x is equal to 1 and R represents amethyl.
 28. The reinforcer according to claim 21, the repeating units ofwhich comprise at least one unit corresponding to formulae (I-bis) or(II-bis):


29. The polybenzoxazine sulfide according to claim 28, the repeatingunits of which comprise at least one unit corresponding to formulae(I-a) or (II-a):


30. The polybenzoxazine sulfide according to claim 29, the repeatingunits of which comprise at least one unit corresponding to formulae(I-a-1), (I-b-1), (II-a-1) or (II-b-1):


31. The reinforcer according to claim 21, the repeating units of whichcorrespond to at least one of the formulae (I-1) or (II-1) below:

in which: X₁ and X₂, which may be identical or different, represent O orS; Ar₁ and Ar₂, which may be identical or different, represent anaromatic group; and Z represents O or (S)_(n), n representing an integergreater than or equal to
 1. 32. The reinforcer according to claim 31,the repeating units of which correspond to at least one of the formulae(I-1bis) or (II-1bis) below:


33. The reinforcer according to claim 21, wherein the reinforcer is inthe form of a yarn, film, tape or cord made of steel.
 34. The reinforceraccording to claim 33, wherein the steel is a bright steel.
 35. Thereinforcer according to claim 33, wherein the steel is at leastpartially coated with a second surface metal selected from the groupconsisting of aluminum, copper, zinc and alloys thereof.
 36. Thereinforcer according to claim 35, wherein the second surface metal isbrass.
 37. A rubber article reinforced with at least one metallic ormetallized reinforcer, at least a surface of which is at least partiallymetallic, the at least partially metallic surface being coated with apolybenzoxazine sulfide, repeating units of which include at least oneunit corresponding to formula (I) or (II):

in which the two oxazine rings are connected together via a centralaromatic group, the benzene ring of which bears one, two, three or fourgroups of formula —S_(x)—R in which x is an integer from 1 to 8 and Rrepresents hydrogen or a hydrocarbon-based group including 1 to 10carbon atoms and optionally a heteroatom chosen from O, S, N and P. 38.A motor vehicle tire reinforced with at least one metallic or metallizedreinforcer, at least a surface of which is at least partially metallic,the at least partially metallic surface being coated with apolybenzoxazine sulfide, repeating units of which include at least oneunit corresponding to formula (I) or (II):

in which the two oxazine rings are connected together via a centralaromatic group, the benzene ring of which bears one, two, three or fourgroups of formula —S_(x)—R in which x is an integer from 1 to 8 and Rrepresents hydrogen or a hydrocarbon-based group including 1 to 10carbon atoms and optionally a heteroatom chosen from O, S, N and P.